Modular walls fabricated from cast concrete blocks of various configurations are commonly used in retaining walls and revetment structures. An example of the former is described in U.S. Pat. No. 2,653,450 Fort, which discloses a modular retaining wall comprising a plurality of vertically stacked hollow, cylindrical blocks. The blocks are formed with slotted ends that engage corresponding slotted ends of adjacent blocks to form an interlocked retaining wall. A concrete footing having a sloping wall supporting surface with an upstanding flange disposed along the high side, permits tilting the retaining wall to minimize lateral displacement thereof from side pressures exerted by retained earthworks and the like. Assistance in this respect is also provided by the outstanding flange.
A concrete revetment wall structure is shown in U.S. Pat. No. 3,375,667 Hard, which discloses two embodiments of crinkle bars useful in building walls without mortar. These bars may be either circular or hexagonal in cross-section and are provided with a regular undulating surface that facilitates interlocking of the bars when stacked.
Another form of interlocking, hollow concrete wall modules is disclosed in U.S. Pat. No. 4,172,680 Brown wherein such modules are used to construct an armouring layer over a breakwater. Each module is cast from concrete in the form of a short, hollow cylinder having outer walls that are hexagonal in cross-section. The armouring layer comprises a single layer of upstanding modules arranged in intimate facial contact with adjacent modules being held together by means of gripping clamps or joining strips disposed in corresponding slots formed int he sidewalls of the modules.
Although the prior art, as typified by the foregoing patents, discloses wall construction modules in the form of cast concrete blocks in cylindrical and other configurations which are in themselves well suited to wall construction, the employment of such modules requires special preparation that is expensive, time-consuming, and is beyond the grasp and capability of a non-skilled person. For example, if the teachings of Fort were followed to construct a small garden retaining wall a trench would have to be dug in which concrete would be poured to form a wall supporting footing having a uniformly sloping upper surface. Undertaking the construction of such a footing requires considerable knowledge, practical experience and expensive wooden forms, none of which are likely to be in possession of the average home-handyman.
Although a simple wall may be built without employing footings as implied by Hard, the absence of constraining means to hold together the ends of a short wall would likely result in an unstable wall structure. Moreover, should the building constraining means be undertaken, which is outside the teachings of Hard, skill, special tools and materials would be required in a manner similar to that expected in the application of the Fort disclosure.
It is apparent that although it is well known to use cylindrical concrete blocks, and other blocks in various forms, to construct walls, the application of such knowledge is wanting in the respective areas of foundations that are simple and easy to install, wall constrainst that are likewise simple to construct and finishing appointments that permit flexibility in wall design, construction and appearance.